Running commentary ... sightjogging is the new way to see St Peter's Square. Photograph: Getty/Giulio Napolitano

If you prefer to stroll leisurely around the tourist attractions of Rome, nose buried in a guide book and stopping off for a cappuccino every hour, then a new service called sightjogging is not for you. But if you're the sporty type and want to sprint around Italy's most beautiful city in the company of a knowledgeable personal trainer, you might want to give it a try. During my hour-long run across the city from the Spanish Steps to the Vatican and back again - a distance of three and a half miles - I learned more than I would in a morning on top of a tourist bus, but it left my heart pounding and my legs feeling like jelly.

Sightjogging is the concept of Carolina Gasparetto, who has lived in Rome for 30 years and has teamed her love of the city with her job as a personal trainer. "The aim is for the run to be as entertaining as possible," she says. "I don't think runners want their heads filled with facts and figures so we try to concentrate on the curiosities and legends connected to the route."

Our run started at the top of the Spanish Steps. Thrilled that we were running down and not up the 138 travertine steps, I was interested to hear that the rococo staircase was commissioned by Pope Innocent XIII in 1723 to connect the church of Trinita dei Monti to the piazza below. We skipped by the Bernini fountain - built in the shape of a boat in 1629 - and then set off down the Via Condotti, whizzing past Prada, Gucci and Alberta Ferretti.

We crossed the Umberto I bridge and made a left towards Castel Sant'Angelo, originally built as a mausoleum by Hadrian in 138AD, down Via della Conciliazione and eventually reached St Peter's Square. While I was catching my breath, Carolina talked about the obelisk in the middle of the piazza which apparently contains a sliver of the cross of Christ.

On our way back we passed Via Borgo Pio where the current Pope lived when he was still Cardinal Ratzinger, then it was across the Sant'Angelo bridge. In the middle ages, the bridge was a favoured place for night-time executions. My legs had had it by now, so we speed-walked back to the starting point and the run ended with outrageously expensive cold drinks in the trendy Caffe Greco, founded in 1760 by a Greek, according to Carolina.

· Sightjogging (0039 347 3353185, sightjogging.it) offers male and female trainers who will pick you up from your accommodation. There are seven differen routes around Rome, €84 per hour for one, €120 per hour for two.

Where to enjoy a refreshing sorbet

Il Gelato di San Crispino is a legendary ice-cream parlour, run by Giuseppe and Pasquale Alongi, who are evangelical about their product: only the freshest, in-season fruit is used. Try the lemon sorbet or wild strawberry ice cream in summer, pomegranate or grape sorbets in autumn. There are three shops: Via Acaia 56; Via della Panetteria 42; Via Bevagna 90.

Where to recarb

After all that exercise, stagger off on unsteady legs to one of Rome's best pizzerias, Fior Fiori (Via della Croce), for a reviving slice of sausage and artichoke pizza, a bargain at €3. In fact, you deserve two.